Fuel compositions with gdi deposit fluidizing agents and methods of use thereof

ABSTRACT

GDI deposit fluidizing additives, liquid fuel compositions including such additives and methods that improve a liquid fuel composition&#39;s GDI performance are provided. A liquid fuel composition may include a major amount of a base gasoline fuel; and 1 to 500 ppm of one or more polyether monohydroxy compounds, with the proviso that the liquid fuel composition is essentially free of fuel detergent additives. The liquid fuel composition provides at least 10% lower particulate emission as a function of time relative to a comparable liquid fuel composition not including the one or more polyether monohydroxy compounds. The GDI deposit fluidizing enhancing additive may include polyether monohydroxy compounds with the butane oxide and propene oxide in a variety of ratios and randomly distributed in the additive.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 63/083,114, filed on Sep. 25, 2020, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

This disclosure relates to Gasoline Direct Injection (GDI) deposit fluidizing additives for liquid fuels, and, more particularly, relates to GDI deposit fluidizing additives including a mixture of polyether monohydroxy compounds that keep clean and improve a liquid fuel's injector nozzle performance.

BACKGROUND OF THE INVENTION

The spark ignited port fuel injection (PFI) engine has been the benchmark standard for the automobile engines over the last few decades. The current spark ignited PFI engine, although highly evolved, is reaching its limits for further optimization. Gasoline direct injection (GDI) engine production is ramping up quickly displacing PFI to meet more stringent vehicle efficiency and emissions regulation requirements. Direct vaporization of the fuel in the combustion cylinder air provides cooling leading to an increase in volumetric efficiency compared to a PFI engine. Lower peak cylinder temperature make GDI engines less prone to knock. This higher resistance to knock can allow for higher compression ratio for higher thermal efficiency or more advanced spark timing for increased torque output. GDI also allows for stratified fuel air operations at less than full load. This yields additional gains in thermal efficiency, mostly due to better thermo-properties of overall lean mixtures and lower heat loss. In addition, the unthrottled operation of GDI engines in lean combustion modes significantly reduces pumping losses at partial loads.

One of the problems experienced with GDI is deposit accumulation on the external areas of the injector nozzle. Most research suggests that these deposits cause emissions and performance problems with GDI. In particular, deposits in the holes affect the fuel flow rate, evaporation rate and mixing with air, thus failing to form the desired air and fuel mixture distribution in the cylinder. In addition, deposits on the external nozzle face surface provide a porous layer for fuel adsorption and desorption which can lead to unwanted soot-producing diffusion flames and/or hydrocarbon emissions.

The injector nozzle assembly has many components and the surfaces in the different component areas experience a variety of deposition environments which are all hastened by the exposure to high levels of heat and reactive combustion vapors from the placement of the injector directly onto the combustion chamber. The composition of the gases in the combustion chamber varies greatly depending on the pistons position in the engine stroke cycle. Oxygen and fuel vapors are rich in the intake and compression stroke, combustion gases are rich in the expansion stroke, and exhaust gases are rich in the exhaust stroke. In the inner area of the nozzle, upstream from the holes and downstream of the needle seat, the sac area mainly encloses bulk fuel at very high temperatures which is stagnant between injections. This area usually maintains a liquid state but some engine conditions could cause complete evaporation of the fuel allowing combustion chamber vapors to make their way to these deeper component surfaces of the nozzle. This will depend on the amount of bulk fuel evaporation that takes place during the interval between fuel injections. Evaporation of the fuel in the holes (also called channels or orifices) between injections as the pressure drops during the power stroke causes the fuel to boil leading to an oscillation of conditions between bulk liquid fuel and combustion chamber vapors. Further downstream of the holes the external nozzle surface (also called face), orthogonal to the channels, mainly experiences combustion chamber vapors with some intermittent liquid fuel wetting the nearer the hole openings during and immediately after fuel injections. The extent of surface wetting in this area depends on the distance from the hole and a variety of factors that can change for different locations in the engine operational map. Wetting can stem from the remaining fuel after the injection has stopped that expands out of the internal areas, and/or capillary action along the surface from the holes. Additional wetting can evolve from fuel leaking from non-perfect seating of the needle valve or bouncing after valve closing.

Deposits on GDI injector nozzle assembly interfere with the proper injection of fuel. These deposits are fundamentally different from the intake valve deposits (IVD) and intake valve stick (IVS) deposits which are a focus area for legacy port fuel injected (PFI) engine designs. The intake valve does not experience combustion gases being closed-off from the combustion chamber during combustion so its deposition environment is substantially different from a GDI injector nozzle that is positioned to interface with combustion chamber. Among other differences to PFI deposits, GDI deposits are formed under radical chain oxidation reactions involving a branching reaction with nitrous oxide. Thus, IVD and IVS are not fuel-dependent in GDI applications and are addressed with different fuel additive chemistries.

The use of a polymeric detergent as a motor fuel additive for cleaning, and keeping clean, the intake system of PFI engines (port fuel injection nozzles, intake ports, and intake valves) is known. These hydrocarbon-based polymeric detergents contain a nitrogen-containing polar head group functionality to impart dispersancy characteristics to the polymer. Many intake valve detergents require the addition of a fluidizer to pass valve stick requirements. In addition to causing IVS deposits many detergents cause higher combustion chamber deposits than the fuel alone. Thus, the use of a fluidizer oil (also known as carrier oils) as a constituent of motor fuel additive mixtures for assisting the detergent in cleaning, and keeping clean the intake system of PFI engines is known.

Based on the foregoing, there is a need for improved deposit control additives for use in fuel compositions to reduce deposits specific to GDI engines.

SUMMARY OF THE INVENTION

The present disclosure provides a novel deposit control fuel additive composition comprising a polyether alcohol additive, without detergent, that is shown to give lower deposits in the nozzle of a GDI injector which provides for lower particulate emissions of the fuel compared to a fuel without the additive or a fuel with an IVD additive package. This disclosure additionally relates to the use of polyether monohydroxy compounds as fuel additives for reducing or preventing deposits in the GDI nozzle injection systems, for reducing the fuel consumption of direct injection engines, and for minimizing the power loss in direct-injection gasoline engines, and in particular in GDI systems. Advantageously, the present disclosure provides improved fuel additives which no longer have the disadvantages of external GDI deposits.

Disclosed herein is a liquid fuel composition. The liquid fuel composition includes a liquid fuel and a GDI deposit fluidizing additive. The GDI deposit fluidizing additive includes one or more polyether monohydroxy compounds with a polyether polymer backbone structure, wherein the side groups contain hydrogen, methyl and ethyl linkages.

Further disclosed herein is another liquid fuel composition. The liquid fuel composition includes a liquid fuel in an amount of about 99 wt. % or greater and an GDI deposit fluidizing additive. The GDI deposit fluidizing additive may include a minor amount of one or more polyether monohydroxy compounds having the following structure:

wherein R₁ is an aromatic, alkylaromatic, aliphatic, linear or branched hydrocarbon chain, R₂, R₃ and R₄ are independently hydrogen or an alkyl hydrocarbon chain having 1 to 5 carbons, and may be either the same or different, and m+n+o are 10 to 40 and are randomly distributed or block copolymers.

Further disclosed herein is a method for improving GDI performance of a liquid fuel in an engine. An example method may include combusting in an internal combustion engine a fuel composition including the liquid fuel and a GDI deposit fluidizing additive. The GDI deposit fluidizing additive includes a polyether monohydroxy compound with randomly distributed alkene oxide monomer units.

Also disclosed herein is a liquid fuel composition for use in a gas direct injection (GDI) engine comprising: a major amount of a base gasoline fuel; and 1 to 500 ppm of one or more polyether monohydroxy compounds, with the proviso that the liquid fuel composition is essentially free of fuel detergent additives, and wherein the fuel composition provides at least 10% lower particulate emission as a function of time as measured by a particle number measurement system described herein relative to a comparable liquid fuel composition not including the one or more polyether monohydroxy compounds.

Still further disclosed herein is a method of maintaining fuel injector cleanliness in a direct injection spark-ignition internal combustion engine using a liquid fuel composition comprising:

providing to a vehicle with a direct injection spark-ignition internal combustion engine a liquid fuel composition comprising a major amount of a base gasoline fuel; and 1 to 500 ppm of one or more polyether monohydroxy compounds, with the proviso that the liquid fuel composition is essentially free of fuel detergent additives, and measuring the particulate emissions as a function of vehicle time-of-use using a particle number measurement system as described herein; and wherein the liquid fuel composition provides at least 10% lower particulate emission as a function of time as measured by a particle number measurement system relative to a comparable liquid fuel composition not including the one or more polyether monohydroxy compounds.

Still also further disclosed herein is method for maintaining deposit free gasoline direct injection injector cleanliness of an internal combustion engine using a liquid fuel composition comprising: providing to a vehicle with a gasoline direct injection injector a liquid fuel composition comprising at least about 99 wt % percent of a base gasoline fuel; and 1 to 500 ppm of one or more polyether monohydroxy compounds, with the proviso that the liquid fuel composition is essentially free of fuel detergent additives, and measuring the particulate emissions as a function of vehicle time-of-use using a particle number measurement system as described herein; and wherein the liquid fuel composition provides at least 10% lower particulate emission as a function of time as measured by particulate emission test relative to a comparable liquid fuel composition not including the one or more polyether monohydroxy compounds.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of the present invention and should not be used to limit or define the invention.

The FIGURE depicts four optical microscopy images (left to right) of the nozzles from each cylinder of a 4 cylinder GDI engine dynamometer tests for six different tests (top to bottom).

DETAILED DESCRIPTION Definitions

“About” or “approximately.” All numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

“Major amount” as it relates to components included within the fuel compositions of the specification and the claims means greater than or equal to 50 wt. %, or greater than or equal to 60 wt. %, or greater than or equal to 70 wt. %, or greater than or equal to 80 wt. %, or greater than or equal to 90 wt. % based on the total weight of the fuel.

“Minor amount” as it relates to components included within the fuel compositions of the specification and the claims means less than 50 wt. %, or less than or equal to 40 wt. %, or less than or equal to 30 wt. %, or greater than or equal to 20 wt. %, or less than or equal to 10 wt. %, or less than or equal to 5 wt. %, or less than or equal to 2 wt. %, or less than or equal to 1 wt. %, based on the total weight of the fuel.

“Essentially free” as it relates to components included within the fuel compositions of the specification and the claims means that the particular component is at 0 weight % within the fuel composition, or alternatively is at impurity type levels within the fuel (less than 100 ppm, or less than 20 ppm, or less than 10 ppm, or less than 1 ppm).

“Fuel detergent additives” means fuel soluble surfactants or a mixture of surfactants with cleansing properties in dilute fuel solutions. Detergents act as an emulsifier that helps bring deposits and fuel together so that the deposit can be easily rinsed away. Detergent molecules arrange themselves into tiny clusters called inverse micelles around deposits precursors and deposits. With the deposit suspended in the center of the inverse micelle the fuel carries the suspended deposits away as the fuel moves through the fuel system. Surfactants can also form a protective films which prevent deposit precursors from accumulating onto the surfaces of the fuel system.

“Other fuel additives” as used in the specification and the claims means other fuel additives that are not specifically recited in the particular section of the specification or the claims. “Oher fuel additives” include antioxidants, friction modifiers and lubricity improvers, antiwear additives, corrosion inhibitors, dehazers/demulsifiers, dyes, markers, odorants, octane improvers, combustion modifiers, antimicrobial agents, and combinations thereof. Other fuel additives as used in the specification and the claims do not include fuel detergent additives. Non-limiting examples of suitable friction modifiers include esters (for example glycerol monooleate) and fatty acids (for example oleic acid and stearic acid). Non-limiting examples of suitable corrosion inhibitors include ammonium salts of organic carboxylic acids, amines and heterocyclic aromatics, for example alkylamines, imidazolines and tolyltriazoles. Non-limiting examples of suitable non-metallic octane improvers include N-methyl aniline and other aniline derivatives. Non-limiting examples of suitable anti-oxidants include phenolic anti-oxidants (for example 2,4-di-tert-butylphenol and 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid) and aminic anti-oxidants (for example para-phenylenediamine, dicyclohexylamine and derivatives thereof). Non-limiting examples of suitable demulsifiers include phenolic resins, esters, polyamines, sulphonates or alcohols that have been reacted with ethylene or propylene oxide.

“Unadditized gasoline” as used in the specification and the claims means any fuels suitable for use in the operation of a direct injection engine prior to the addition of performance additives, which are generally mixtures of detergents and other performance additives. Examples of unadditized gasoline are for example, unleaded motor gasolines and so-called reformulated gasolines which typically contain both hydrocarbons of the gasoline boiling range and fuel-soluble oxygenated blending agents (“oxygenates”) such as alcohols, ethers, and other suitable oxygen-containing organic compounds. The fuel may be a mixture of hydrocarbons boiling in the gasoline boiling range. The fuel may include straight chain or branch chain paraffins, cycloparaffins, olefins, aromatic hydrocarbons, or any mixture of these. The fuel may be a gasoline derived from straight run naphtha, alkylate gasoline, thermally and catalytically reformed stocks, visbreaker stocks, and coker stocks boiling in the range from about 25 to about 250° C.

Compositions and Methods of the Instant Disclosure

One of the problems experienced with GDI is deposit accumulation on the injector nozzle external surfaces. Most research suggests that these deposits cause emissions and performance problems in vehicles with GDI fuel systems. The extent of fuel wetting on the nozzle face decreases the greater the distance from the holes where at some point the surface only experiences combustion chamber vapors and no liquid state unless impingement of the fuel spray and additives takes place onto the surface. Accumulation of deposits in these more distal areas makes up what is commonly referred to as combustion chamber deposits (CCD). Deposits on GDI injector nozzles are formed under much harsher conditions than intake valves in PFI. Higher temperatures and pressures combined with reactive vapor chemistry create a much different environment in GDI.

Deposit accumulation in these different areas stems from auto-oxidation, pyrolysis of residual fuel and cylinder oil and reactions with the combustion chamber gases. The mechanisms of deposit accumulation in these different areas is very different and very complex and can involve both liquid and vapor depositions processes. Deposits on the GDI injector nozzle are based on fundamentally different chemistries and conditions (temperature, pressure, combustion gases, and flow behavior) compared to intake valve deposits (IVD). Thus, the additive solutions to control deposition in these different area will also be different.

Detergents themselves are only operational in wetted areas and are not capable of stopping deposit accumulation if not in the liquid state. In fact, some detergents themselves can cause deposits considering they are solid once the fuel evaporates and would only add to the deposit accumulation. For example, some of the intake valve detergents cause deposits on the valve stem in port fuel injection systems because they are not fluid-like once the fuel boils off and is the reason for the addition of fluidizer additives to avoid detergent build up on the stems. Another example is the additional buildup of combustion chamber deposits (CCD) that results from detergent additives. Detergents can also contribute to engine oil dilution in the course of daily operation causing oil thickening in the interval between oil changes. Since the detergent buildup in the engine oil is proportional to the level of motor fuel additives and because of the increasingly longer periods between oil changes, it is an object of the present disclosure to avoid the use of nonvolatile, thermally stable detergents.

GDI injector deposits are an important issue to solve as they can reduce particulate emissions. The deposit and particulate issue is a priority for the industry to manage. The present disclosure relates to gasoline compositions effective for reducing gasoline direct injection injector face deposits that cause particulate issues with GDI which research has shown to increase particulate emissions in GDI engines.

Disclosed herein are chemistries designed to keep modern GDI nozzle surface areas clean by maintaining fluidity on surface areas of the nozzle that are intermittently devoid of liquid phase during operation. Evaporation allows deposit precursors to adhere to each other and adhere to the surface to form injector deposits. Fluidity and miscibility facilitate dislodging of the deposit precursors into the burning fuel in subsequent sprays rather than solidifying to the surface especially near the injector holes. Once dislodged, the GDI additives are designed to easily degrade in the combustion gases from their low degradation temperatures.

Removing these nozzle face deposits avoids emission issues associated with late diffusion flame, which is a source of soot production, and temporal and spatial spray variations which hinder optimal GDI performance.

Maintaining fluidity in the external nozzle can be challenging given the hot environment. It's a feature of the present disclosure that the accumulation of solid deposits on the external surface (face) could be lessened by maintaining fluidity in these areas with properly optimized additives with respect to viscosity, thermal stability, volatility and solubility. An optimized GDI additive for lowering external deposits by maintaining fluidity may balance one or more of these characteristics.

-   -   1. High miscibility with the fuel and decomposed products that         accumulate on the nozzle external surfaces;     -   2. High boiling point to assure the thin liquid film remains         throughout the cycle;     -   3. Low viscosity in the neat state (after fuel evaporates) to         facilitate fluidity within the thin film to facilitate         dislodging; and/or     -   4. Appropriate thermal stability to remain intact to achieve         above but readily decomposes when dislodged into the combustion         chamber so not to contribute to CCD.

Accordingly, there remains a need for additives for a GDI engine that are able to achieve keep clean GDI performance. The current disclosure provides a new low viscosity, high boiling point additive with appropriate solubility and thermal stability that has been found to keep clean the face of the nozzle.

Non-limiting examples of suitable GDI deposit fluidizing compounds for use in fuels include, but are not limited to, monohydroxy polyethers of Formula (1) below:

wherein R₁ is an aromatic, alkylaromatic, aliphatic, linear or branched hydrocarbon chain, R₂, R₃ and R₄ are independently hydrogen or an alkyl hydrocarbon chain having 1 to 5 carbons, and wherein R₂, R₃ and R₄ may be either the same or different, and m+n+o are integers ranging from 10 to 40 and are randomly or block distributed or a combination of randomly and block distributed copolymers.

Another non-limiting example of a suitable GDI deposit fluidizing additive for use in fuels includes a polyether monohydroxy compound of Formula (1) above wherein R₁ is an aromatic, alkylaromatic, aliphatic, linear or branched hydrocarbon chain, R₂, R₃ and R₄ are independently hydrogen or an alkyl hydrocarbon chain having 1 to 5 carbons, and wherein R₂, R₃ and R₄ may be either the same or different, and m+n+o are 10 to 40 and are randomly distributed or block copolymers to produce a neat polymer viscosity between 1 and 2,000 cSt at 40° C., or more particularly between 5 and 1,000 cSt at 40° C., even more particularly between 10 and 500 cSt at 40° C., and still even more particularly between 20 and 250 cSt at 40° C.

Yet another example of a suitable GDI deposit fluidizing additive including a polyether monohydroxy compound that includes an alkyloxide group initiated polymer of Formula (2) below:

The longer hydrocarbon chain alkoxide initiator, such as dodecanol, provides high fuel solubility. Dow Chemical sells polyether monohydroxy products under the tradename of UCON™ OSP formulated fluids and lubricants and base stocks (see Lube Magazine, Lube-Tech “Oil Soluble Synthetic Polyalkylene Glycols A New Type of Group V Base Oil”, No. 104, August 2011, incorporated herein by reference). Methods of production and properties of these polymers are disclosed in U.S. Pat. Nos. 2,841,479 and 2,782.240 and Kirk-Othmer's “Encyclopedia of Chemical Technology’, 2nd Ed., Volume 19, p. 507, also incorporated herein by reference. In general, the polyether monohydroxy compound are mixtures of compounds that differ in polymer chain length. However, their properties closely approximate those of the polymers represented by the average composition and the polydispersity, which is the ratio of the weight average molecular weight to the number average molecular weight of the polymer.

As previously described, the GDI deposit fluidizing additive including a polyether monohydroxy compounds can be used to maintain a liquid fuel composition's GDI performance. The GDI deposit fluidizing additive may be included in the liquid fuel composition in any suitable amount as desired for improving GDI performance. In some embodiments, the GDI deposit fluidizing composition can be present in the liquid fuel composition in an amount ranging from 1 ppm to 1000 ppm, or 30 ppm to 300 ppm, or 50 to 275 ppm, or 70 to 250 ppm, or 90 to 200 ppm, or 100 to 160 ppm, or 120 to 140 ppm. The e amount of the GDI deposit fluidizing additive used in the fuel may be based on a number of factors, including, but not limited to, fuel system operating conditions, the particular length of the polymer and substituents thereon, and the liquid fuel's hydrocarbon components.

In some embodiments, the GDI deposit fluidizing additive including a polyether monohydroxy compound may be included in a liquid fuel composition to extend the GDI performance of the liquid fuel composition, which may result in improved combustion and lower Particulate Number (PN) emissions. In some embodiments, the GDI deposit fluidizing composition can be present in the liquid fuel composition to lower the PN emissions at least 5%, or more particularly at least 10%, or more particularly at least 25%, even more particularly a least 50% and still even more particularly at least 90% compared to the same liquid fuel composition without the GDI deposit fluidizing additive. The GDI performance may be extended as compared to the liquid fuel composition without the GDI deposit fluidizing additive, for example, to maintain particulate emission similar to a new injector. As used herein, the GDI vehicle PN emissions is determined using a PN test system.

In some embodiments, the GDI deposit fluidizing additive may be introduced into a fuel system of an internal combustion engine. In some embodiments, the GDI deposit fluidizing combination may be combined with the liquid fuel composition in the internal combustion engine. In some embodiments, the GDI deposit fluidizing composition may be introduced into the internal combustion engine as a component of the liquid fuel composition. In the combustion chamber of the internal combustion engine, the liquid fuel composition may be then burned.

In addition to the GDI deposit fluidizing additive, the liquid fuel composition may further include a liquid fuel. Combinations of different liquid fuels may also be used. Motor gasoline includes a complex mixture of relatively volatile hydrocarbons blended to form a fuel suitable for use in spark-ignition engines. Motor gasoline, as defined in ASTM Specification D4814, is characterized as having a boiling range of 50° C. to 70° C. at the 10-percent recovery point (referred to as T10 boiling point) to 185° C. to 190° C. at the 90-percent recovery point (referred to as T90 boiling point).

As used herein, “base gasoline fuel” or “base gasoline fuel composition” refer to hydrocarbon compositions having a boiling range of 25 to 250° C., or 30 to 240° C., or 35 to 230° C., or 40 to 220° C., or 45 to 210° C., or 50 to 200° C., or 55 to 190° C., or 60 to 180° C. The base gasoline fuel may also be a blend of two or more distinct base gasoline components that fall within the above boiling range. Base gasoline fuel is also commonly referred to as “naphtha.”

The liquid fuel compositions disclosed herein may also optionally include one or more oxygen containing compounds in a minor amount in the overall composition. Non-limiting examples of oxygen containing compounds include, an alcohol, an ether, or combinations thereof. In some embodiments, the liquid fuel compositions may include oxygen containing compounds including, but are not limited to, methanol, ethanol, diethyl ether, and methyl t-butyl ether. In some embodiments, the liquid fuel may include a mixture of a motor gasoline and ethanol. The one or more oxygen containing compounds may be included in the liquid fuel composition at from 5 to 85 wt. %, or 10 to 80 wt. %, or 15 to 75 wt. %, or 20 to 70 wt. %, or 25 to 65 wt. %, or 30 to 60 wt. %, or 35 to 55 wt. %, or 40 to 50 wt. %, or 45 to 49 wt. %.

The base gasoline or base liquid fuel may be present in the liquid fuel composition with the GDI deposit fluidizing additive in any suitable amount. As previously described, the liquid fuel may include any suitable liquid fuel, including a combination of two or more different fuels. In some embodiments, the liquid fuel or base gasoline fuel may be present in the liquid fuel composition in an amount ranging from 1 to 99 wt. %, or 5 to 95 wt. %, or 10 to 90 wt. %, or 15 to 80 wt. %, 20 to 75 wt. %, or 25 to 70 wt. %, or 30 to 60 wt. %, or 55 to 99 wt. %, or 60 to 90 wt. %, or 65 to 85 wt. %, or 70 to 80 wt. %, or 5 to 20 wt. %.

Polyether additives have been used in combination with IVD detergents additives as carrier fluids to resolve IVS issues with PFI fuel systems (see for example, U.S. Pat. No. 5,004,478, and WO 2018/169905 A1, herein incorporated by reference in their entirety). Patent Publications have disclosed IVD detergent additives that include, but are not limited to, Mannich reaction products formed by condensing a long chain aliphatic hydrocarbon-substituted phenol or cresol with an aldehyde, and an amine (U.S. Pat. No. 3,634,515), long chain aliphatic hydrocarbons having an amine or a polyamine attached thereto (U.S. Pat. No. 6,140,541A), polyalkenyl succinimides (U.S. Pat. Nos. 3,219,666, 4,234,435, 3,172,892), and quaternary ammonium salt detergents (USP 10479950B2, US 20190264119A1, U.S. Pat. No. 8,961,623B2, US 20200024536A1, USP 10308888B1, U.S. Pat. No. 9,574,149B2, U.S. Pat. No. 9,340,742B1, USP 10173963B2, US0160142A1) and prior art detergent examples described in above patents that include fuel-soluble nitrogen containing salts, amides, imides, imidazolines, esters, and long chain aliphatic hydrocarbon-substituted dicarboxylic acids or their anhydrides or mixtures thereof. Each of the above referenced patent publications are incorporated by reference herein.

Solving deposit issues on valve tulips and stems with fuel additives in PFI systems is feasible seeing the fuel comes into contact with these components. In GDI no fuel is injected into the intake manifold, so no fuel spray is directed on the intake valves tulip so it is not possible to clean, or keep clean IVD. Fuel must be considered to interact with the intake valves in only a secondary fashion, such as through blowback upon intake valve opening which is highly limited in addressing IVD.

Although both IVD and GDI nozzle deposits are carbon deposits there are significant compositional differences between them because of the conditions under which these deposits are formed. GDI nozzle deposits are linked more closely to CCD of a PFI engine, because of the slight resemblance in the physical and chemical environment and fuel additives for address CCD are lacking. Additives for solving IVD issues in an induction system will be much different than additives for solving issue with GDI nozzles seeing the heat, pressure, reactive chemistry environment is different. The deposit control additives designed for one area of the fuel system often don't work in others of the fuel system. Over the past several decades, gasoline detergents have evolved to control fuel system deposits in specific areas which affects vehicle performance and emissions. Simple low MW amine detergent which were called carburetor detergents developed in the 1950's prevented throttle body deposits that caused rough idling, but they were not able to clean other parts of the fuel system. Adverse effects in the form of deposits were sometimes seen in piston ring belts and elsewhere. As highlighted in SAE 700456, “while these additives do a good job preventing carburetor and, in some cases, intake manifold and port deposits, they are not very effective in removing preformed deposits in these areas. In addition, these materials usually have either no effect or a detrimental effect on intake valve deposits.” and in SAE902104, “removing deposit from carburetor throttles bodies. However, they were not effective in handling deposits in other parts if the carburetor such as the air bleeds, or in the rest of the engine intake system”.

Carburetors were replaced by Port Fuel Injection (PFI) in the late 1970's. With this new technology came new problems. Hot fuel degradation at tip of injector caused injector fouling which lead to loss of power and hesitation and increased emissions. Higher treat levels of carburetor detergent additives helped with injector fouling but caused issues in other areas of the induction system such as IVD. As highlighted in SAE902104, “[t]he use of carburetor detergents had a resurgence in 1985 after problems with port fuel injector deposits surfaced and automobile manufacturers requested that additives be used to keep injectors clean. However, to obtain the necessary cleanliness performance, nearly double the carburetor detergent treatment rate was required. In many cases, this increased intake valve deposits.” Similarly, the deposit control additives designed to address PFI systems to keep clean and clean up PFI injectors and intake valves would not necessary work for GDI nozzles. Deposits formed on these different parts will have differing chemical and physical properties.

EXAMPLES

To facilitate a better understanding of the present disclosure, the following examples of certain aspects of some embodiments are given. In no way should the following examples be read to limit, or define, the entire scope of the disclosure.

Example 1

The base fuel used in this example was a regular unadditized unleaded E0 gasoline fuel. The base fuels were blended with GDI deposit fluidizing additive candidates at a relatively low treat rate of 100 ppm. For comparison the base fuel was additized with a Top-Tier IVD additive package at 382 ppm. The additive properties are described in Table 1. Performance of the additives was determined by comparing the base fuel with and without the additive. The GDI performance tests was a injector keep clean tests that used a Mini Cooper Vehicle (BMW B48 direct injection spark ignition engine) on a chassis dynamometer test bench running at constant speed/load for 12 hr. Operating conditions used are shown in Table 2 below.

TABLE 1 Additives types and decomposition temperatures Viscosity cSt Additive at 100° C. T_(D50) (° C.)^(a) IVD additive package (unknown NA  303^(b) mixture w/solvent) BASF Palatinol ® TOTM (Tris 28  282 (2-Ethylhexyl) Trimellitate) ExxonMobil Chemical SpectraSyn 6 274 6 (Polyalphaolefin) ExxonMobil Chemical Esterex NP 5 270 451 (Neopentyl polyol esters) Dow UCON OSP-32 (Polyether copolymer 6  226^(c) of butylene oxide and propylene oxide)^(d) ^(a)TGA temperature for 50% weight loss. TGA conditions; air purge gas, 10° C./min heating rate. ^(b)50% weight loss after removal of additive package solvent. ^(c)TGA thermal curve was a single thermal event. Other candidates and the IVD additive package exhibited multistage decomposition of a residue after the initial thermal decomposition event. ^(d)Formula (2) where in m and n are chosen to produce a 32 cSt at 40° C. viscosity grade additive.

TABLE 2 BMW B48 direct injection spark ignition engine operation conditions Engine speed 3,500 1/min Engine load 2 bar BMEP equivalent (=32 Nm) Fuel injection pressure 120 bar Fuel feed temperature 35° C. Fuel flow 5.3 kg/h Test length 12 hr

Performance was monitored by three metrics associated with this test; injector flow rate shifts w/time, particle number (PN) emissions with time, and nozzle deposit appearance at EOT (optical microscopy images). PN emissions were measured using an AVL M.O.V.E PN PEMS iS unit to measure solid particle number with a 23 nm cut-off. Sensor probe was connected to the Mini Cooper vehicle tailpipe exhaust system. The PEMs system uses a diffusion charger sensor to determine the particle number concentration emitted in the vehicle exhaust stream as a function of time. The instrument is compliant with the technical requirements for measuring PN emissions defined in the Real Driving Emissions (RDE) regulations. Installation, calibration and operation of the PEMS is described in the product manual and is standard practice for those skilled in the art of measuring vehicle exhaust emissions. Other in-situ methods are suitable for the PN measurement such as Engine Exhaust Particle Sizer (EEPS) Spectrometer, a Condensation Particle Counter (CPC) and an Electrical Low Pressure Impactor (ELPI).

The following Table 3 shows the changes in injector flow rate and PN of unadditized base gasoline fuel and additized base gasoline fuels. As used herein, “base gasoline fuel” or “base gasoline fuel composition” refers to a hydrocarbon composition having a boiling range of 25 to 250° C., or 30 to 240° C., or 35 to 230° C., or 40 to 220° C., or 45 to 210° C., or 50 to 200° C., or 55 to 190° C., or 60 to 180° C. PN is related to the nozzle cleanliness which remained low by using the GDI deposit fluidizing additive additives.

TABLE 3 Summary of Mini Cooper testing results Amount Flow rate PN × 10¹² Run Fuel (ppm) shift (%)¹ [#/km]² 1 Base fuel (BF) no additives −10.6 6.3 2 BF + IVD additive package 382 −3.5 5.8 3 BF + Palatinol ® TOTM 100 −10.2 6.8 4 BF + SpectraSyn 6 100 −5.9 4.8 5 BF + Esterex NP 451 100 −7.7 11.0 6 BF + UCON OSP-32 100 −8.7 3.5 ¹Average first half hour vs last half hour of test. ²Average of last half hour of test The PN was the lowest for the base fuel with UNCON OSP-32. The level of PN emissions corresponds to the level of nozzle face cleanliness with lower PN corresponding to a cleaner injector nozzle face which was easily observed from their visual appearance. FIG. 1 highlights the appearance of the injectors after testing.

The test gasoline with no additives (FIG. 1, row 1) exhibited deposits on the injector nozzle causing an increase of PN and reduced flow (Table 3, Run 1).

The fully formulated IVD package in the test gasoline (FIG. 1, row 2) shows significant face deposits however the sac and holes are cleaner leading to the lowest flow rate shift emphasizing the role detergents played when a liquid state was maintained.

Of the 4 GDI additive candidates tested to investigate nozzle keep clean performance (PALATINOL (FIG. 1, row 3), SPECTRASYN 6 (FIG. 1, row 4), MCP 684 (FIG. 1, row 5), and UCON OSP-32 (FIG. 1, row 6), OSP-32 exhibited the best performance with the lowest observable amount of face deposits and lowest PN (44% lower than base fuel without additive). OSP-32 alone maintained a nozzle free of deposits in areas with low fluidity, without the presence of detergents. The data highlights how a properly designed GDI deposit fluidizing agent, which facilitates surface wetting, can improve the PN performance of a GDI engine. OSP-32 has the best combination of ideal characteristics with respect to solubility, viscosity, non-volatility and appropriate thermal stability. OSP-32 readily decomposes which avoids additive residues in the combustion chamber.

We found in our testing that a GDI fluidizing additive with an ideal balance of properties highlighted above, the nozzle face remained clean which improves PN emissions compared to the base fuel case without additive and with an IVD additive package. The low viscosity, low volatility helps maintain a liquid film on the nozzle face surface in the extreme high temperature environment which helps remove the deposits precursors and avoids deposit precursor solidification. Deposit in this area of the nozzle are associated with a pronounced increases in PN and hydrocarbon emissions.

PCT/EP Clauses:

1. A liquid fuel composition for use in a gas direct injection (GDI) engine comprising: a major amount of a base gasoline fuel; and 1 to 500 ppm of one or more polyether monohydroxy compounds, with the proviso that the liquid fuel composition is essentially free of fuel detergent additives, and wherein the fuel composition provides at least 10% lower particulate emission as a function of time as measured by a particle number measurement system described herein relative to a comparable liquid fuel composition not including the one or more polyether monohydroxy compounds.

2. The liquid fuel composition of clause 1, wherein the polyether monohydroxy compounds are represented by the formula:

wherein R₁ is an aromatic, alkylaromatic, aliphatic, linear or branched hydrocarbyl group, R₂, R₃ and R₄ are independently hydrogen or an alkyl hydrocarbon chain having 1 to 5 carbons, and R₂, R₃ and R₄ are the same or different, and m+n+o are integers ranging from 10 to 40 and are either randomly distributed or block distributed copolymers.

3. The liquid fuel composition of clause 2, wherein the weight average molecular weight of the polyether monohydroxy compounds is from 500 to 3000.

4. The liquid fuel composition of clauses 2 or 3 wherein R₁ is a linear or branched aliphatic hydrocarbyl group of 5 to 20 carbon atoms.

5. The liquid fuel composition of clauses 1-4 further including 5 wt. % to 45 wt. % of one or more oxygen-containing compounds.

6. The liquid fuel composition of clause 5, wherein the one or more oxygen containing compounds are selected from the group consisting of methanol, ethanol, diethyl ether, methyl t-butyl ether, and combinations thereof.

7. The liquid fuel composition of clause 6, wherein the one or more oxygen-containing compounds is ethanol.

8. The liquid fuel composition of clauses 1-7, further including other fuel additives selected from the group consisting of corrosion inhibitor, lubricity additive, octane improver, demulsifier, and combinations thereof.

9. A method of maintaining fuel injector cleanliness in a direct injection spark-ignition internal combustion engine using a liquid fuel composition comprising: providing to a vehicle with a direct injection spark-ignition internal combustion engine a liquid fuel composition comprising a major amount of a base gasoline fuel; and 1 to 500 ppm of one or more polyether monohydroxy compounds, with the proviso that the liquid fuel composition is essentially free of fuel detergent additives, and measuring the particulate emissions as a function of vehicle time-of-use using a particle number measurement system as described herein; and wherein the liquid fuel composition provides at least 10% lower particulate emission as a function of time as measured by a particle number measurement system relative to a comparable liquid fuel composition not including the one or more polyether monohydroxy compounds.

10. The method of clause 9, wherein the polyether monohydroxy compounds are represented by the formula:

wherein R₁ is an aromatic, alkylaromatic, aliphatic, linear or branched hydrocarbyl group, R₂, R₃ and R₄ are independently hydrogen or an alkyl hydrocarbon chain having 1 to 5 carbons, and R₂, R₃ and R₄ are the same or different, and m+n+o are integers ranging from 10 to 40 and are randomly distributed or block copolymers.

11. The method of clause 10, wherein the weight average molecular weight of the polyether monohydroxy compounds is from 500 to 3000.

12. The method of clauses 10-11, wherein R₁ is a linear or branched aliphatic hydrocarbyl group of 5 to 20 carbon atoms.

13. The method of clauses 9-12, wherein the liquid fuel composition further includes 5 wt. % to 45 wt. % of one or more oxygen-containing compounds.

14. The method of clause 13, wherein the one or more oxygen containing compounds are selected from the group consisting of methanol, ethanol, diethyl ether, methyl t-butyl ether, and combinations thereof.

15. The method of clause 14, wherein the one or more oxygen-containing compounds is ethanol.

16. The method of clauses 9-15, wherein the liquid fuel composition further includes other fuel additives selected from the group consisting of corrosion inhibitor, lubricity additive, octane improver, demulsifier, and combinations thereof.

17. A method for maintaining deposit free gasoline direct injection injector cleanliness of an internal combustion engine using a liquid fuel composition comprising: providing to a vehicle with a gasoline direct injection injector a liquid fuel composition comprising at least 99 wt % percent of a base gasoline fuel; and 1 to 500 ppm of one or more polyether monohydroxy compounds, with the proviso that the liquid fuel composition is essentially free of fuel detergent additives, and measuring the particulate emissions as a function of vehicle time-of-use using a particle number measurement system as described herein; and wherein the liquid fuel composition provides at least 10% lower particulate emission as a function of time as measured by particulate emission test relative to a comparable liquid fuel composition not including the one or more polyether monohydroxy compounds.

While the invention has been described with respect to a number of embodiments and examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope and spirit of the invention as disclosed herein. Although individual embodiments are discussed, the invention covers all combinations of all those embodiments.

While compositions, methods, and processes are described herein in terms of “comprising,” “containing,” “having,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. The phrases, unless otherwise specified, “consists essentially of” and “consisting essentially of” do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of the invention, additionally, they do not exclude impurities and variances normally associated with the elements and materials used.

For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. 

What is claimed is:
 1. A liquid fuel composition for use in a gas direct injection (GDI) engine comprising: a major amount of a base gasoline fuel; and 1 to 500 ppm of one or more polyether monohydroxy compounds, with the proviso that the liquid fuel composition is essentially free of fuel detergent additives, and wherein the fuel composition provides at least 10% lower particulate emission as a function of time as measured by a particle number measurement system described herein relative to a comparable liquid fuel composition not including the one or more polyether monohydroxy compounds.
 2. The liquid fuel composition of claim 1, wherein the polyether monohydroxy compounds are represented by the formula:

wherein R₁ is an aromatic, alkylaromatic, aliphatic, linear or branched hydrocarbyl group, R₂, R₃ and R₄ are independently hydrogen or an alkyl hydrocarbon chain having 1 to 5 carbons, and R₂, R₃ and R₄ are the same or different, and m+n+o are integers ranging from 10 to 40 and are either randomly distributed or block distributed copolymers.
 3. The liquid fuel composition of claim 2, wherein the weight average molecular weight of the polyether monohydroxy compounds is from 500 to
 3000. 4. The liquid fuel composition of claim 2 wherein R₁ is a linear or branched aliphatic hydrocarbyl group of 5 to 20 carbon atoms.
 5. The liquid fuel composition of claim 1 further including about 5 wt. % to about 45 wt. % of one or more oxygen-containing compounds.
 6. The liquid fuel composition of claim 5, wherein the one or more oxygen containing compounds are selected from the group consisting of methanol, ethanol, diethyl ether, methyl t-butyl ether, and combinations thereof.
 7. The liquid fuel composition of claim 6, wherein the one or more oxygen-containing compounds is ethanol.
 8. The liquid fuel composition of claim 1, further including other fuel additives selected from the group consisting of corrosion inhibitor, lubricity additive, octane improver, demulsifier, and combinations thereof.
 9. A method of maintaining fuel injector cleanliness in a direct injection spark-ignition internal combustion engine using a liquid fuel composition comprising: providing to a vehicle with a direct injection spark-ignition internal combustion engine a liquid fuel composition comprising a major amount of a base gasoline fuel; and 1 to 500 ppm of one or more polyether monohydroxy compounds, with the proviso that the liquid fuel composition is essentially free of fuel detergent additives, and measuring the particulate emissions as a function of vehicle time-of-use using a particle number measurement system as described herein; and wherein the liquid fuel composition provides at least 10% lower particulate emission as a function of time as measured by a particle number measurement system relative to a comparable liquid fuel composition not including the one or more polyether monohydroxy compounds.
 10. The method of claim 9, wherein the polyether monohydroxy compounds are represented by the formula:

wherein R₁ is an aromatic, alkylaromatic, aliphatic, linear or branched hydrocarbyl group, R₂, R₃ and R₄ are independently hydrogen or an alkyl hydrocarbon chain having 1 to 5 carbons, and R₂, R₃ and R₄ are the same or different, and m+n+o are integers ranging from 10 to 40 and are randomly distributed or block copolymers.
 11. The method of claim 10, wherein the weight average molecular weight of the polyether monohydroxy compounds is from 500 to
 3000. 12. The method of claim 10, wherein R₁ is a linear or branched aliphatic hydrocarbyl group of 5 to 20 carbon atoms.
 13. The method of claim 9, wherein the liquid fuel composition further includes about 5 wt. % to about 45 wt. % of one or more oxygen-containing compounds.
 14. The method of claim 13, wherein the one or more oxygen containing compounds are selected from the group consisting of methanol, ethanol, diethyl ether, methyl t-butyl ether, and combinations thereof.
 15. The method of claim 14, wherein the one or more oxygen-containing compounds is ethanol.
 16. The method of claim 9, wherein the liquid fuel composition further includes other fuel additives selected from the group consisting of corrosion inhibitor, lubricity additive, octane improver, demulsifier, and combinations thereof.
 17. A method for maintaining deposit free gasoline direct injection injector cleanliness of an internal combustion engine using a liquid fuel composition comprising: providing to a vehicle with a gasoline direct injection injector a liquid fuel composition comprising at least about 99 wt % percent of a base gasoline fuel; and 1 to 500 ppm of one or more polyether monohydroxy compounds, with the proviso that the liquid fuel composition is essentially free of fuel detergent additives, and measuring the particulate emissions as a function of vehicle time-of-use using a particle number measurement system as described herein; and wherein the liquid fuel composition provides at least 10% lower particulate emission as a function of time as measured by particulate emission test relative to a comparable liquid fuel composition not including the one or more polyether monohydroxy compounds.
 18. The method of claim 17, wherein the polyether monohydroxy compounds are represented by the formula;

wherein R₁ is an aromatic, alkylaromatic, aliphatic, linear or branched hydrocarbyl group, R₂, R₃ and R₄ are independently hydrogen or an alkyl hydrocarbon chain having 1 to 5 carbons, and R₂, R₃ and R₄ are the same or different, and m+n+o are integers ranging from 10 to 40 and are randomly distributed or block copolymers.
 19. The method of claim 18, wherein the weight average molecular weight of the polyether monohydroxy compounds is from 500 to
 3000. 20. The method of claim 18, wherein R₁ is a linear or branched aliphatic hydrocarbyl group of 5 to 20 carbon atoms. 